Recently in the study of transcription factors concerned with marker genes expression in adipocytes differentiation, peroxisome proliferator activated receptor (abbreviated as PPAR hereinafter), which is one of intranuclear receptors, has been focused. cDNAs of PPAR were cloned from various kinds of animals, and plural isoform genes were found, particularly in mammals three types of isoforms (α, δ, γ) are known (see J. Steroid Biochem. Molec. Biol., 51, 157 (1994); Gene Expression., 4, 281 (1995); Biochem Biophys. Res. Commun., 224, 431 (1996); Mol. Endocrinology., 6, 1634 (1992)). PPAR γ isoform is predominantly expressed in adipose tissues, immune cells, adrenal gland, spleen, small intestine. PPAR α isoform is mainly expressed in adipose tissue, liver, retina, and PPAR δ isoform is widely expressed without specificity for tissue (see Endocrinology., 137, 354 (1996)).
On the other hand, the following thiazolidine derivatives are known as agents for the treatment of non-insulin dependent diabetes mellitus (NIDDM) and are hypoglycemic agents which are used for the improvement of hyperglycemia in the patients suffering from diabetes. They are also effective for the improvement of hyperinsulinemia, glucose tolerance and decrease of serum lipid and therefore they are thought to be considerably hopeful as agents for the treatment of insulin resistance. 
One of the target proteins in the cells of these thiazolidine derivatives is exactly PPAR γ and it is resolved that they enhance the transcription activity of PPAR γ (see Endocrinology., 137, 4189 (1996); Cell., 83, 803 (1995); Cell., 8, 813 (1995); J. Biol. Chem., 270, 12953 (1995)). Therefore, a PPAR γ activator (agonist) which enhances its transcription activity is thought to be hopeful as a hypoglycemic agent and/or a hypolipidemic agent. Furthermore, since a PPAR γ agonist is known to promote the expression of PPAR γ protein itself (Genes & Development., 10, 974 (1996)), an agent which increases the expression of PPAR γ protein itself as well as PPAR γ activating agent is also thought to be clinically useful.
PPAR γ is related to adipocytes differentiation (see J. Biol. Chem., 272, 5637 (1997) and Cell., 83, 803 (1995)). It is known that thiazolidine derivatives which activate this receptor promote adipocytes differentiation. Recently it was reported that thiazolidine derivatives increase fat mass and cause man to gain weight and to become obese (see Lancet., 349, 952 (1997)). Therefore, it is also thought that antagonists which inhibit PPAR γ activity and agents that decrease the expression of PPAR γ protein itself are also clinically applicable. On the other hand, a compound that phosphorylates PPAR γ protein and decreases its activity is reported (Science., 274, 2100 (1996)). This implies that an agent which does not bind on PPAR γ protein as a ligand, but inhibits its activity is also clinically applicable.
From these, PPAR γ activators (agonists) and PPAR γ regulators for its expression that can increase the expression of the protein itself are expected to be useful as hypoglycemic agents, hypolipidemic agents, and agents for prevention and/or treatment of diseases associated with metabolic disorders such as diabetes, obesity, syndrome X, hypercholesterolemia and hyperlipoproteinemia etc., hyperlipidemia, atherosclerosis, hypertension, circulatory diseases and overeating etc.
On the other hand, antagonists that inhibit the transcription activity of PPAR γ or PPAR γ regulators that inhibit the expression of the protein itself are expected to be useful as hypoglycemic agents and agents for prevention and/or treatment of diseases associated with metabolic disorders such as diabetes, obesity and syndrome X etc., hyperlipidemia, atherosclerosis, hypertension and overeating etc.
The following fibrate compound (e.g. chlofibrate) is known as a hypolipidemic agent. 
And, it is also resolved that one of the target proteins in the cells of fibrate compounds is PPAR α (see Nature., 347, 645 (1990); J. Steroid Biochem. Molec. Biol., 51, 157 (1994); Biochemistry., 32, 5598 (1993)). From these facts, PPAR α regulators which can be activated by fibrate compounds are thought to have a hypolipidemic effect, and so they are expected to be useful as agents for prevention and/or treatment of hyperlipidemia etc.
Besides, it has been recently reported that PPAR α possesses anti-obese activity in the specification of WO 9736579. In addition, it was reported that the elevation of high density lipoprotein (HDL) cholesterol level and the reduction of low density lipoprotein (LDL) cholesterol, very low density lipoprotein (VLDL) cholesterol and triglyceride levels were induced by activation of PPAR α (J. Lipid Res., 39, 17 (1998)). It was also reported that composition of fatty acids in blood, hypertension and insulin resistance were improved by administration of bezafibrate which is one of fibrate compounds (Diabetes., 46, 348 (1997)).
Therefore, agonists that activate PPAR α and PPAR α regulators that promote expression of PPAR α protein itself are useful as hypolipidemic agents and agents for treatment of hyperlipidemia, and are expected to have HDL cholesterol level-elevating effect, LDL cholesterol and/or VLDL cholesterol levels-lowering effect, inhibition on the progress of atherosclerosis and anti-obese effect. Therefore, they are thought to be hopeful agents for the treatment and/or prevention of diabetes as hypoglycemic agents, for the improvement of hypertension, for the relief from risk factor of syndrome X and for the prevention of occurrence of ischemic coronary diseases.
On the other hand, few reports are found on ligands that activate PPAR δ significantly or on biological activities associated with PPAR δ. PPAR δ is sometimes called PPAR β, or it is also called NUC1 in humans. Until now, as for activity of PPAR δ, it is disclosed in the specification of WO 9601430 that hNUC1B (PPAR subtype whose structure is different from that of human NUC1 in one amino acid) inhibited the transcription activities of human PPAR α and thyroid hormone receptor. Recently in the specification of WO 9728149, it was reported that the compounds, which possessed high affinity to PPAR δ protein and which could activate PPAR δ significantly (i.e. agonists) were found out and that they had HDL (high density lipoprotein) cholesterol level-elevating activity. Therefore, agonists that can activate-PPAR δ are expected to have HDL cholesterol level-elevating effect, and so they are expected to be useful for the inhibition on the progress of atherosclerosis and treatment thereof, as hypolipidemic agents and hypoglycemic agents, for the treatment of hyperlipidemia, as hypoglycemic agents, for the treatment of diabetes, for the relief from risk factor of syndrome X, and for the prevention of occurrence of ischemic heart diseases.
For example, the specification of WO98/00403 discloses that an isoquinoline derivative represented by formula (A) (wherein, A0A is etc., R2A is hydrogen atom, C1-4 acyl, etc., R5A is COOH, etc., R6A is hydrogen atom, C1-4 alkyl, aryl, etc., R7A is hydrogen atom, C1-4 alkyl, etc, WA is (CH2)nA, YA is O, S, etc., nA is integer of 1-4) or a salt thereof are useful for the treatment of hyperglycemia and hyperlipidemia (necessary parts were extracted from the description of groups).